1. Field of the Invention
This invention relates to a welding gun of plastics, particularly to one taking advantage of a welding wire to reinforce combining strength of two pieces of plastics.
2. Description of the Prior Art
Plastics are usually apt to create residual stress while being manufactured or stress concentration owing to foreign force, posing formation of cracks or splits. Strong glues or other adhesives have been often used to seal such crack or splits. However, because of different abrasion rates of the plastics and the adhesives, sealed cracks of the plastics may damage again after serving for a certain period of time. Although the cracks can be repaired by glues with the same abrasion rate as that of the plastics to avoid damaging again due to different abrasion rates, repaired cracks may still be damaged after a certain period of time as they have a lower strength than that of the plastics themselves.
For preventing damages caused by different abrasion rates and different strength between plastics and glues, conventional jointing tools have as well been used, regularly basing on contacting, heated air, high frequency or supersonic; they are all theorized by conducting heat to make two pieces of plastics instantly melted and fused together, called welding effect, able to prevent repaired cracks from re-damaging as those repaired by glues or adhesives.
Although cracks repaired by the conventional jointing tools can be prevented from damaging again, they may have disadvantages like displacement, surface deformation, distortion and residual stress. Moreover, using such conventional jointing tools to proceed with combining operation not only costs high, but also involves a complicated operation.